// @ts-check

import maybeJsonParse from "../common/maybeJsonParse.js";
import * as base64url from "../common/base64url.js";

/**
 * Parse a location hash into `name` and `bytes`.
 * @param {string} hash
 * @returns {null | { name: string, bytes: Uint8Array }} The parsed data, or `null` if the hash can't be parsed.
 */
export default (hash) => {
  const normalizedHash = decodeURI(hash.replace(/^#/, ""));

  const parsed = maybeJsonParse(normalizedHash);
  if (!parsed || typeof parsed !== "object") {
    console.warn("Couldn't parse hash as JSON object");
    return null;
  }

  if (
    !("name" in parsed) || (typeof parsed.name !== "string") ||
    !("bytes" in parsed) || (typeof parsed.bytes !== "string")
  ) {
    console.warn("Hash fields missing or invalid type");
    return null;
  }

  const { name } = parsed;
  if (!name) {
    console.warn("Name is empty");
    return null;
  }

  const bytes = base64url.parse(parsed.bytes);
  if (!bytes || !bytes.byteLength) {
    console.warn("Bytes is empty");
    return null;
  }

  return { name, bytes };
};